能不能帮忙翻译下面这些话(来自英国数学教程 function ) 顺便解释一下它所包含的数学术语 和词组 谢谢
a function may be thought of as a rule which takes each member x of a set and assigns,or maps,it to some value y known as its image. x maps to y y is the image of x f(x) is read as 'f of 'x . alternative notation